Electrostatic chucks are known devices used in semiconductor manufacturing processes. Such chucks eliminate the need for the prior used mechanical clamping devices that were often difficult to use with precision, and often introduced contaminants to the semiconductor manufacturing chambers. Chucks support the substrates within the semiconductor wafer manufacturing or processing chamber. Designers have developed electrostatic chucks that comprise ceramics in combination with an embedded metallic conductor. These chucks are often referred to as “ceramic chucks”. Ceramic chucks hold an electrostatic charge that secures a substrate, such as a wafer in a semiconductor manufacturing chamber. Some designs rely upon an adhesive-type bonding of the assembly to secure the metallic conductor within multiple ceramic layers, and to form the chuck.
Known devices contain multilayer ceramic components supported on a metallic base. However such known designs have prolonged charging and discharging periods of up to 10 seconds or longer. Such charging and discharging periods are viewed as impractical in most modern semiconductor manufacturing processes that require faster throughput. Indeed, metal bases in the chuck construction are prone to electrical bridging or arcing that can result in leakage between electrodes and the base. Such arcing can drain off the stored charge that holds the work piece in place, and exposed metal base results in arcing damage in plasma chambers.
Hybrid chucks have been developed for securing work pieces with an electrostatic charge. Commonly owned U.S. Pat. No. 6,754,062 discloses such a hybrid chuck comprising a dielectric base for supporting the hybrid chuck. The hybrid chuck itself includes a top surface with a conductive covering layer that covers at least a portion of the top surface of the dielectric base. The conductive layer receives a current creating an electrostatic charge and is non-metallic for maintaining the charge without significant eddy current losses in the presence of dynamic electromagnetic fields present during semiconductor manufacturing. The top working surface covers the conductive layer and is flat for holding work pieces upon receiving current to create the electrostatic charge in the conductive layer.
However, in the design of electrostatic chucks, it is increasingly desirable to reduce the total capacitive load on the semiconductor tools using the electrostatic chucks. Known chucks have not provided such a desired reduction. Further, the problem of arcing with known electrostatic chucks has not been completely addressed as metal base heat sink arcing typically occurs to some extent. An improved electrostatic chuck that addresses these issues would be highly advantageous.